Fuzzy Control of a Moving Coil Electromagnetic Valve Actuator for an Automotive Camless Engine

In a camless engine, where each valve is independently actuated, fuel economy, emissions, and torque output performance of the engine can be greatly improved. Valves controlled by the moving coil EMVA are supposed to follow a desired trajectory. Electronically-controlled variable valve timing should meet stringent criteria on performance, reliability and acoustics that are necessary for automotive applications. This paper addresses the trajectory tracking control of a moving coil electromagnetic valve actuator (EMVA). The dynamic model for the EMVA system is developed. Building a PID control system with state-feedback requires either measuring each of the state variables (the actual displacement the valve travels, the velocity of the valve and coil current) or using a state observer which increases both the cost and the uncertainty of the system. A new control algorithm is suggested which includes a feed-forward fuzzy inference control and a PID control in the feed-back loop. The proposed algorithm limits the measured parameters to one which is the valve displacement. The fuzzy inference system has two inputs (which are the desired valve displacement and the rate of change of the desired displacement) and one output (the control voltage). It was constructed upon using ANFIS (adaptive neuro-fuzzy inference system) and the training data sets are acquired from the proposed system utilizing full state feedback and PID control. The results showed that fully- variable valve actuation has been achieved with respect to valve lift, tracking accuracy, and seating velocity. It was found that the synthesized controller is feasible, can sustain the uncertainties in the system, and the control supply voltage does not exceed its limiting value. Accordingly, the fuel consumption and the acoustic emissions can be reduced and the output torque performance is improved.